Cadmium Sulfide 3D Photonic Crystal with Hierarchically Ordered Macropores for Highly Efficient Photocatalytic Hydrogen Generation

Abstract

Cadmium sulfide is a potential candidate for photocatalytic water splitting. However, CdS nanoparticles have a high recombination rate of photoinduced carriers induced by aggregation. Therefore, decreasing the recombination rate and increasing the migration rate of photogenerated carriers are essential to drive the development and application of CdS in hydrogen production. In this study, we design CdS with a three-dimensional ordered macroporous (3DOM) structure using polymethylmethacrylate as a template. It not only retains the excellent visible light response of CdS but also improves the easy recombination of photogenerated carriers in CdS nanoparticles by taking advantage of the unique ability of mass transfer, charge separation, and migration in the 3DOM structure. Meanwhile, the highly ordered periodic structure of 3DOM CdS can produce a slow photon effect of photonic crystals to obtain more photoinduced carriers. In particular, we found that a suitable stop-band position is beneficial to maximize the utilization of the slow photon effect. The photocatalytic hydrogen evolution rate of Pt–CdS is considerably improved after constructing the 3DOM structure. This study provides a new design strategy of ordered macroporous sulfide catalysts to achieve high photocatalytic activity.

Hierarchically Periodic Macroporous CdS–ZnO Heterojunctions with Multiple Quantum Well-like Band Alignments for Efficient Photocatalytic Hydrogen Evolution without a Cocatalyst

“…Compared with the HPM heterojunctions, the H 2 evolution activity of CdS–ZnO grains (CZGs) prepared by destroying HPM structures is reduced by 44.61%, largely being caused by the disordered distribution of grains. The disordered CZGs make the carrier utilization process unbalanced and hinder the efficient separation of photogenerated carriers . Also, the disappearance of the pore channel results in a decrease in mass transfer.…”

“…Meanwhile, the carrier utilization process is unbalanced due to the random distribution of heterojunctions on the pore walls, and the presence of numerous bare non-heterogeneous interfaces makes charge separation/transfer very limited . Moreover, many homogeneous interfaces still exist in the HPM structures prepared by this strategy, and the grain boundaries are regarded as recombination centers for photogenerated electrons and holes. , Therefore, if two photocatalysts can be alternately bridged in the form of grains as the HPM skeletons (Figure b), the carrier recombination at the homogeneous grain boundaries will be replaced by unique recombination at the Z-scheme under light illumination. Different from the former, this elective interface recombination, driven by band bending and a built-in electric field, allows the spatial separation of holes in the oxidation edge and electrons in the reduction edge .…”

Semi Transparent Three-Dimensional Macroporous Quaternary Oxynitride Photoanodes for Photoelectrochemical Water Oxidation

“…3DM thin film photoanodes with an inverse opal structure have been fabricated for oxides, sulfides, and nitrides by using colloidal sphere templates. − The inverse opal structure serves to induce multiple scattering of light to enhance the effective absorption length of the semiconductor and to promote minority carrier collection at the semiconductor–electrolyte interface . This differs somewhat from general nano/macroporous photoelectrodes, where the advantages of a porous structure can be impaired by diffusion-limited replenishment of reactants through tortuous geometries.…”

Advances in Enhancing the Stability of Cu-Based Catalysts for Methanol Reforming

“…Hydrogen is a well-known clean energy carrier, and fuel cells can convert the chemical energy in fuel hydrogen and oxidant oxygen into electricity (sustainable energy). Hydrogen can come from many sources [4,5], for example, photolysis of water for hydrogen production [6][7][8], traditional fossil fuel hydrogen production [9,10], biomass hydrogen production [11][12][13], and hydrogen production from water electrolysis [14,15]. In recent years, more and more studies have been conducted on methanol steam reforming.…”